U.S. Pat. No. 4,693,941, granted Sep. 15, 1987 to Ostapchenko, discloses PET compositions containing a small amount of a terpolymer of ethylene containing carboxyl groups which may be partly or completely neutralized to a divalent metal salt form, and a reinforcing filler, such as glass fibers. Example VII discloses an ethylene/n-butyl acrylate/methacrylic acid terpolymer. In addition, Ostapchenko requires a reinforcing filler to be present. Ostapchenko is concerned in producing sheets with his composition which are readily thermoformable and have good thermoforming radius ratios.
U.S. Pat. No. 4,172,859, granted Oct. 30, 1979 to B. N. Epstein, discloses multiphase thermoplastic molding compositions containing 60-99 weight percent of polyester matrix resin, and 1-40 weight percent of ionomer having a particle size in the range of 0.01-3.0 microns. The ionomer has a tensile modulus of less than 1/10th the tensile modulus of the matrix resin. Among the ionomers disclosed and exemplified by Epstein in such compositions are poly(ethylene/iso-butylacrylate/methacrylic acid) and poly(ethylene/methyl acrylate) both ionomers being neutralized with zinc. The homopolymer of the softening comonomers in these ionomers, namely iso-butyl and methyl, both have a glass temperature of of -24.degree. C. or higher. Such compositions are characterized as toughened as compared with unmodified polyester compositions. Epstein does not teach an ethylene/n-butyl acrylate/methacrylic acid neutralized with zinc. In addition, Epstein does not teach a specific glass transition temperature for the homopolymer of the softening comonomer within the ionomer.
U.S. Pat. No. 4,772,652, granted Sep. 20, 1988 to Yoshifumi et al., discloses a polyester resin composition comprising a copolyester, an ionomer used as a nucleating agent, and a reinforcing filler. These polyester resin compositions are characterized by toughness, impact strength and moldability.
U.S. Pat. No. 4,914,156, granted Apr. 3, 1990 to Howe, discloses a blow moldable polyester composition containing 85-95 parts by Weight of polyester, 5-15 parts by weight of an epoxide polymer, 0.01-3.0 parts by weight of an ionomer in particular a zinc ionomer of ethylene/methacrylic acid, and 0.1-3.0 parts by weight of a fibrillatable polytetrafluoroethylene resin.
U.S. Pat. No. 4,771,108, granted Sep. 13, 1988 to MacKenzie, discloses a flex-resistant oriented polyester film comprising a blend of polyethylene terephthalate (PET) resin, a polyolefin incompatible with the PET and an ionomer resin such as a partially neutralized ethylene/methacrylic co- or ter-polymer.
U.S. Pat. No. 4,753,980, granted Jun. 28, 1988 to Deyrup, discloses toughened thermoplastic polyester compositions comprising 60-97 weight percent of a polyester and 3-40 weight percent of an ethylene copolymer such as ethylene/methacrylate/glycidyl methacrylate.
U.S. Pat. No. 4,659,767, granted Apr. 21, 1987 to Dunkle et al., discloses an impact modified linear saturated polyester blend comprising 50-86 percent by weight of a linear saturated polyester and 14-50 percent by weight of an impact modifying amount of (1) an acrylate-containing core-shell polymer and (2) a copolymer of an .alpha.-olefin having 2-8 carbon atoms and includes an ethylene/methacrylic acid copolymer neutralized with zinc.
U.S. Pat. No. 4,506,043, granted Mar. 19, 1985 to Ogawa et al, discloses a glass-reinforced thermoplastic polyester composition containing 100 parts by weight of PET, 5 to 200 parts by weight of glass fibers, 0.05 to 3 parts by weight of a mold release agent and an ionomer such as metal neutralized ethylene/ethyl acrylate/methacrylic acid.
U.S. Pat. No. 4,303,573, granted Dec. 1, 1981 to Ostapchenko, discloses a molding blend containing PET, an ionomeric terpolymer, such as, ethylene/iso-butyl acrylate/methacrylic acid neutralized with zinc and a second terpolymer.
U.S. Pat. No. 4,294,938, granted Oct. 13, 1981 to Berr et al., discloses a polyester molding composition containing PET, a reinforcing material, an ionomer such as ethylene/methacrylic acid copolymer neutralized with sodium and a silicon resin. These composition improve the heat aging resistance to oxidative discoloration of PET resins.
U.S. Pat. No. 4,801,649 granted Jan. 31, 1989 to Statz, discloses a thermoplastic blend of an ethylene/n-butyl acrylate/methacrylic acid neutralized with zinc and copolymer with material selected from the group consisting of nylon, polypropylene, propylene-ethylene copolymer, linear polyethylene, and ethylene/unsaturated carboxylic acid copolymer.